In recent years, imide salts such as LiN(SO2F)2 have been attracting attention as supporting salts added to electrolytes used for lithium ion secondary batteries. KN(SO2F)2 or NaN(SO2F)2, or mixtures thereof have also been attracting attention as electrolytes for molten salt batteries.
Methods for producing KN(SO2F)2 and KN(SO2F)2 are disclosed in the following reference. In Non Patent Literature 1, urea and fluorosulphonic acid are subjected to reaction to produce HN(SO2Cl)2 which is then subjected to reaction with KF in a nitromethane or dichloromethane solvent to obtain KN(SO2F)2.
Meanwhile, there is a need for a simplified production method of imide salts typically including LiN(SO2F)2, KN(SO2F)2, NaN(SO2F)2 and the like compared to conventional methods. This is because the conventional production methods require many steps for obtaining desired products from raw materials and also are time consuming due to the lengthy fluorination reaction.    Non Patent Literature 1: Z. Anorg. Allg. Chem, 2005, 631, p. 55-59